Patent GB-1499353-A (GB)
Title: Balance testing machines
IPC: B29D30/06
Filed: 1975-02-04
Abstract: 1499353 Balance testing objects such as tyres RANSBURG CORP 4 Feb 1975 [4 Feb 1974] 4805/75 Heading G1X A machine for testing pneumatic tyres or other inflatable annular objects for static balance comrises a support 8, 9 an object carrier 10 mounted on support for universal pivotal movement, passages in the carrier and the support whereby an object retained on the carrier can be inflated, and valve means for maintaining the object inflated whilst being tested. Construction:-The machine, as shown, has a cylinder block 12 defining upper and lower cylinders 15, 18 in which work respective pistons 19, 25. A pedestal 43 is bolted to the cylinder block and has a member 47 including an upper concave spherical bearing surface 56 co-operating with a complementary convex spherical bearing surface on an element 49 to form a universal pivot joint. Air is supplied through passages 51, 52, 53 to the joint, to reduce friction, and is exhausted through passages 58, 59, 60. A vertically movable sleeve 61 is positioned around the pedestal 43 and is normally biased upwardly by springs (not shown) to allow pivoting of the element 49, but when air is supplied through ports 77, 79 is moved downwards such that an annular clamp plate 62 engages the element 49. The pedestal 43 has a central chamber 58 housing a spring 89 biasing a hollow piston 84 upwards to engage a wall 88 of the element 49. An actuater rod 20 secured to the piston 19 has a diametrically elongate projection 92 which can engage a shoulder 94 in the piston 84 to disengage the piston from the wall 88 and allow pivoting of the element 49. A pipe 97a and holes 95, 96 connect the interior of the piston 84 with a source of compressed air. The carrier 10 comprises a body 104 secured on the element 49 and having a lower rim element 108. A central chamber 123 in the body 104 can communicate via hole 93 in element 49 with the interior of the hollow piston 84. Communication is normally prevented by a spring-biased closure disc 134 obstructing the hole 93, but on raising of the actuator rod 20 an extension 137 forces the closure disc 134 away from the hole. The carrier 10 includes a plurality of locking pins 144 which can be moved radially outwards against spring-bias by downward movement of a frusto-conical element 155 mounted on a plunger 130 to lock an upper rim element 110 to the body 104. The upper rim element 110 can be raised from and lowered on to the carrier body 104 by a carriage 11 controlled by a piston and cylinder device 188, 189 and guided by guide rods 198. The carriage 11 has a reciprocable latch 204 actuated by a piston and cylinder device 214, 215 for engaging or releasing a groove 173 in a plunger 161 on the upper rim element 110. Operation:-On starting, the carriage 11 is in its upper position with the latch 204 engaged with the upper rim element 110. A tyre is placed on the lower rim element 108 while fluid is supplied through ports 77, 79 such that the clamp plate 62 prevents pivoting of the element 49. The piston and cylinder device 188, 189 is then operated to lower the carriage 11 until the upper rim element 110 engages the carrier whereupon a plunger head 165 is forced upward to operate a limit switch 223. Fluid is then admitted to cylinder 15 and causes piston 19 and actuator rod 20 to descend thereby allowing plunger 130, and closure disc 134 to descend under the action of springs 136, 135. Downward movement of plunger 130 and consequent movement of the frusto-conical element 155 forces the lock pins 144 radially outward to lock the upper rim element 110 to the carrier body 104. The latch 204 is then released and the carriage 11 is raised. Air is then admitted through pipe 97a and holes 95, 96, 97, around projection 92 through hole 93 into chamber 123, and thence through radial holes 121 to inflate the tyre. Upon further lowering of the piston 19, the piston 25 moves down and operates a limit switch 38 whereupon fluid is evacuated from ports 77, 79 thereby releasing the engagement of the clamp plate 62 with element 49 and allowing pivotal movement of the carrier and tyre. A bubble level mounted on an arm 114 on the carrier may be used to detect any unbalance in the tyre. In addition a counterweight may be attached to the carrier diametrically opposite the arm 114. After the tyre has been tested, the pistons 19, 25 are raised and air is evacuated from the tyre in the reverse direction to its path for inflation. Piston 19 is then raised further resulting in the unlocking of pins 144 whereupon carriage 11 descends, latch 204 re-engages the groove 173 and the carriage 11 lifts the upper rim element 110 off the carrier body 104 to allow removal of the tyre.